I disagree with Sheldon Brown about putting the best tire on the front. We had a poll here last month because of this very discussion about most flats occur on the rear, thus why would you put a more worn thus more flat prone tire in the rear? Why would you want the more hassle of changing the rear more often? The only reason is because of a blowout, it's easier to handle a blowout on the rear-rubbish-at least as far as clinchers are concerned! First of all sudden blowouts on bike tires are rare, thus losing control with a flat front or rear is not a major concern as long as you don't panic and lock the brakes up on the rim with the flat tire. In fact I have had flats while rounding turns and never had a crash then either; and clinchers stay on their rims far better then tubulars do in these situations. So again, my logic is to put the best tire to the rear, and this is the way I have been doing it since switching to clinchers back in 1987. In fact I knew a person that had a sudden blow out on a rear tire and because of the more weight on the rear the load forces tore the tire off the rim and he had quite a thrilling ride, whereas a front sudden blow out I had did not cause that kind of problem at all (both blowouts were on clinchers), I just brought it to a slow stop riding on the sidewalls. Also clinchers are not as prone to blowouts as tubulars are thus any flat are slow air leakage, so you know your flatting and have time to respond to it.

Now normally I will run the rear tire from the time that it's new to about 1,600 miles then I will transfer it to the front and slap on the new on on the rear. After about 1600 miles go by I discard the front and repeat the process. This last time I experimented with a 28 in the rear and thought it would be wider than the 26 front but the 28 was only taller; so when the 28 wears out I will be going back to 26's all around since I don't need a taller tire and I cannot move it either.

BUT LOOKIE HERE MAN; Sheldon Brown has probably forgotten more about bikes then I will ever hope to know; so take what I say with a grain of salt.